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Galaxy clustering in the Canada-France Legacy Survey

Galaxy clustering in the Canada-France Legacy Survey. Colleen Corradi Brannigan, “Sofronia”. H.J. McCracken and folks from TERAPIX and VVDS consortia. For the conference “Galaxies and Structures through cosmic time”, Venice, Italy March 2006.

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Galaxy clustering in the Canada-France Legacy Survey

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  1. Galaxy clustering in the Canada-France Legacy Survey Colleen Corradi Brannigan, “Sofronia” H.J. McCracken and folks from TERAPIX and VVDS consortia For the conference “Galaxies and Structures through cosmic time”, Venice, Italy March 2006 “Every time I describe a city I am saying something about Venice. . . . To distinguish the other cities' qualities, I must speak of a first city that remains implicit. For me it is Venice.”- From Italo Calvino’s Invisible Cities

  2. Input catalogues: The CFHTLS deep fields • Input photometric catalogues: CFHTLS-T03 deep fields processed at TERAPIX/CFHT • Ultra-deep photometrically uniform catalogues (chip-to-chip variations are less than 1%) • Catalogues reach ~27AB in ugriz (>30hr integrations in some filters!) • Total effective area: 3.1 deg2 in four fields • We can compute ‘real’ cosmic variance error bars • Photometric redshifts calibrated using 8,000 VVDS spectra available in the d1 field • Accuracy: around 3% in the redshift range 0.1<z<1.2 Ilbert et al. astro-ph/0603217

  3. Computing the comoving correlation length From photo-zeds We are using photozeds and so we must weight w() by the enclosed area of the object’s pdf in the redshift interval under investigation

  4. Can we measure galaxy clustering with photo-zeds?... You bet! • In the CFHTLS-D1 we can make a direct comparison between clustering with z-photo and z-spec after applying the same selection function 0.7<z<0.9 i*<24.0 Correlation length vs. z wp spectro/photzed Slope vs. z

  5. Type-selected volume limited samples-I i*<24.5, 0.2<z<1.5, 3.1 deg2 Type=1, Ngal=24,662 Type=2, Ngal=33,427 Type=3,Ngal=96,380 Type=4,Ngal=113,183 All types, Ngal=267,652

  6. Type-selected volume limited samples-II i*<24.5, 0.2<z<1.5, -22<MB-5log h<-17 • Type 1 galaxies correspond to the reddest galaxies in the colour-magnitude plane • Type 4 galaxies are the bluest objects at each redshift range 0.2<z<0.5 0.7<z<0.9 1.1<z<1.3 0.5<z<0.7 0.9<z<1.1

  7. Luminosity dependent clustering at low- and high-z i*<24.5 0.2<z<0.6 0.7<z<1.1 Slope Correlation length

  8. Conclusions • Galaxy clustering can be reliably measured using photometric redshifts • We investigate the dependence of comoving correlation length as a function of luminosity with “honest” error bars • For galaxies with L<L*, the clustering amplitude depends only weakly on luminosity for late types • For galaxies of the same absolute luminosity, clustering amplitude depends strongly on type at all redshifts • Some indication that the relative bias between late and early types is larger for faint galaxies in low redshift bins

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